Farm animal manure is a slurry containing liquids and solids in suspension. Such manure must be held in holding reservoirs near a barn such as in-ground tanks or lagoons, commonly referred to as manure pits. A by-product of keeping animal manure is that it can, when required, be spread by suitable spreaders on fields as a fertilizer. The apparatus for spreading the manure normally comprises a closed tank mounted on a vehicle and communicating with a spreader. When required, the manure in the holding reservoir must be transferred into the spreading tanks by suitable pumps.
However, the manure in the holding reservoir tends to separate and the solids may settle to form a thick layer at the bottom of the reservoir and may also form a thick solid crust on the surface of the liquids. Such crust has a consistency of dry peat moss and must therefore be broken up before it can be mixed with the liquid into a “pumpable” slurry and be transferred from the reservoir into the spreading apparatus. It is necessary, therefore, to provide an apparatus for both mixing the solids and forming a slurry with the liquids in the reservoir as well as to have a pumping apparatus for pumping the so-formed slurry into the tank for the spreading apparatus.
The inventor has obtained U.S. Pat. No. 4,594,006 issued on Jun. 10, 1986 and U.S. Pat. No. 5,100,303 issued on Mar. 31, 1992, both of which are herein incorporated by reference, relating to a manure pump for mixing and pumping manure pits. As described in the above-mentioned patents, opposed first and second impellers are provided for drawing solids and liquids towards the pump. The ratio of solids relative to the liquids being pump may in some instances be too important to provide for the formation of an easily “pumpable” slurry, thereby requiring longer mixing operations.
While the apparatuses described in the above patents have proven to be efficient, the breaking up of the crust and other solid contents and the mixing thereof with the liquid contents remain time consuming.
Also conventional mixing and pumping apparatus also typically comprises a valve for selectively connecting the outlet of the pump in flow communication with either a drainage pipe or a re-circulation pipe. The valve is operational to divert the incoming flow to a selected one of the pipes. Under certain operation conditions, such flow deviation may result in clogging problems.
There is thus a need for a new apparatus for mixing and pumping manure slurries.